POCUS is becoming extremely useful at investigating these patients as it allows great visualization of the tendon and sheath showing lacerations, foreign bodies and infection. Being a dynamic exam, you can have the patient move their digits and watch the tendons slide.

An important trick is to consider use of a water bath to immerse the affected area. The probe is then floated in the water above. This provides an acoustic “step off” for improved image quality and the patient can easily move the finger while the probe hovers above.

This young man probably had micropunctures with sharp plastic at work 2 days ago. He presented with a painful, somewhat red, swollen finger mainly proximally near the PIP joint. Movement and pressure were painful. Sounds like tenosynovitis. Still it can’t hurt (me) to look. POCUS revealed no joint fluid but did reveal fluid along the flexor tendons. So it looks like flexor tenosynoivitis, too.

For bonus points can anyone identify what is likely the A3 pulley/annular ligament?

Comments (2)

I was wondering why the fluid was in that periodic pattern. I guess it corresponds to the parts that aren’t constricted by the annular ligaments. If you hadn’t have brought it up, I would never have thought of that. Amazing what you can see (and appreciate if you’re thinking!).

Sometimes you have to look carefully to appreciate the pulleys. Scanning the finger in short axis can help appreciate the annular component of the pulley. A thin echogenic line just above the flexor tendons is usually visible on high resolution scanning. In conditions like trigger finger you can even appreciate a thickening of the pulley. For a nice summary article of scanning the hand and wrist you can look at: Olubaniyi et. al. J Ultrasound Med 2013; 32:901–914 (Free download from the Journal of Ultrasound in Medicine website.)